Treatment of petroleum tar acids fractions



Patented ze, 1946 2 2,393,699

Vittorio Molinari, North Plain field, n. J., asslgnor vt'o Bakelite Corporation, a corporation of New ersey No Drawing. Application September 11, 1943, I ScrlalNo. 501,991 v 'cj oiaims. (01. 260-627) This invention relate to the preparation and v (1) Treating the crude tar acids with aqueous isolation from crude tar acids of phenols suitable caustic soda and decanting the phenolate solufor reaction with formaldehyde to yield resins; tion from thesupernatant oily layer in the usual th e ph ls c mprise, Phenol (monohydmXy manner; this step is thesame' as that for exj benzene) andthe homologous methyl phenols tracting crude tar acids from middle and heavy which include cresols', xylenols, trimethyl phenols oils of high temperature coal carbonization; Y and tetramethyl phenols. At present it is the (2) Heating the aqueous solutions to temperacommon practice to recover these phenols from 'tures that cause substantial dehydration and crude tar acids produced in the high temperature fusion of the crude sodium phenolate, for it is carbonizationof bituminous-coals; and the phel0 essential to the effectiveness of, the succeeding nols are obtained bywashing the tar acids with step that the mass be at fusion temperature; and

aqueous caustic soda, separating bydecanting '(3), Blowing the molten mass with a stream of from the'oily'layer the'water layer carrying the air carrying a definite amount of water vapor; phenolates in solution, concentrating the water The residue remaining after the blowing is dislayer to eliminate oily and'pyridlne impurities, it! solved in water, acidified and rectified toyield a andliberating the phenol 'mixtures by means mixture of free phenols, When the-liberated of carbon'dioxide or sulfuric acid. The mixtures phenol mixture is fractionated into phenol,cresol of phenols are usually fractionated under vacuum and xylnol cuts, the'fractions have substantially into phenol, cresol and xylenol cuts, for each cut the same specific gravitiesthat characterize frachas a definite reactivity with formaldehyde. tions of the same boiling range'obtained by high Other large potential but unused sources of temperature coal distillation and the same rates phenols for resin production are crude tar acids of reactivity with formaldehyde.

resulting from the cracking of petroleum. A rea- The phenolates, prepared according to step 1,

son for the non-use of these tar acids is the presare concentrated in step 2 by boiling f wa r and ence in them of monohydric phenols with side 5 continuing the heating to the fusion temperature chains longer than the methyl, for instance, ethyl. of the crude phenolate, generally about 280 C. butyl, etc., and these higher alkyl phenols show and above. The blowing with air carrying a defivery low reactivity and interfere with or inhibit nite'proportion of water vapor in step 3 is accomthe resin-forming reactions of the much more replished by bubbling the stream of air through active phenol and methyl phenols with formwater held at a fixed temperaturewhereby the aldehyde; generally the higher alkyl phenols conair becomes saturated at that temperature; as a stitute from 5 to 10 per cent of the phenolic conrule, bubbling through water at about 90 C. has tent, and their presence is indicated by the relabeen found to supply the amount of water retively low specific gravity of the phenol cuts com-- quired and to maintain the fused phenolate mass pared with those of the same temperature'range in the condition of concentration without bec0mobtained from high temperature coal carbonizaing unduly dry and yet remain in a fused condition crude tar acids. Another reason for non-use tion. An excess of air over the quantity required is the presence in the crude tar acids of 0bjeccauses decomposition at the high fusion temperationable amounts of other compounds, here classed ture of the useful phenol and methyl phenols, and as impurities, such as neutral oil, sulfur com- 9 it is accordingly necessary to stop the air flow pounds (mercaptans), nitrogen bases (pyridine), before such decomposition begins; the amount is thiophenols, etc.; these impurities, and especially determined by preliminary experiments on samthe sulfur compounds, are not eliminated by the "'ples of the molten mass and analyses of the reusual process applied to the derivation of phesults. After the step of blowing, the offensive nols from crude tar acids produced in high tem-- odor, due to mercaptans or other sulfur comperature coalcarbonlzation. It is to the recovery pounds, is found to have disappeared; and either of the useful resin-forming phenol fractions free the remaining objectionable compounds are defrom the higher alkyl phenols and the impurities composed into simpler low-boiling. products car that the present application is directed as a conried off in the air stream, or they are compounds tinuation-in-part of the copending application of high boiling points remaining'in the residue Serial No. 324,322 filed March 16, 1940. from which the useful phenols are readily set free.

It has been found that the petroleum crude tar In a German Patent No. 584,857 to Meyer the acids can be treated to eliminate not only the inability of purifying brown coal (lignite) tar higher alkyl phenols but the impurities as well acids by oxidation followed by steam distillation by a process involving the steps: I at 3. is explained, and the method to which oil bath, while steam is introduced,,to about 220 C. until a solid residue is formed which residue is dissolved in water and acidified to separate cresol; such a method, however, is ineffective for the treatment of petroleum tar acids. To begin with, oxidation with air at ordinary temperature of the phenolates in water solution causes no change in the objectionable higher alkyl phenols or any de-. crease in the impurities with the exception of the mercaptans; and oxidation with air alone of the phenolates in fused condition is not feasible on account of the energetic reaction with consequent decomposition and formation of high boiling products and tarry matter constituting a loss that may reach to 40 to 50 per cent of the original mass. In the next place steam distillation of the phenolate solution without the simultaneous passage of air has no appreciable effect as is demonstrated by the following:

, Example 1.-Five thousand (5000) grams of a crude tar acids fraction, collected from petroleum-cracking products over a distillation range of from 220-240 C., showed a specific gravity of 1.000 at 20 C. This was mixed with 1000 grams of water and 1545 grams of 98% caustic soda and then concentrated. The phenolate so formed was heated to fusion (300-340 C.) and a stream of steam was passed through the fused mass for- 3 hours. The fusion was dissolved in water, sprung with sulfuric acid and distilled under a vacuum to dryness. The bulk of the tar acids passed over in the distillation, and in all 96 per cent of the tar acids was recovered, the loss being accounted for in the transfers of the material. The specific gravity after this treatment was again 1.000 at 20 C., thus showing no change with respect to the higher alkyl phenol content.

It follows from the foregoing that steam distillation preceded by oxidation as separately applied steps cannot be effective. But the surprising results obtained by the conjoint action of steam and air in treating the fused mass is shown by the following:

Example 2.Four thousand (4000) rams of the same rawmaterial as in Example '1 were treated with 1200 grams of caustic soda in 6000 cc. of water, dehydrated and heated to fusion (320-360 0.). A current of air saturated with ladies were formed; and the water solution of the phenoiates, after separation by decantation, was concentrated by evaporating in a gas-heated stainless .steelretort while being agitated with a scraping type agitator. When the molten mass reached a temperature of approximately 280 C..

a current of air, which. had previously been bubbled through water heated to 90 C., was blown through the molten mass until 10 to 15 cubic feet of air per gallon of tar acid used had passed through; during this operation the temperature of the molten mass was elevated to and maintained at 320 to 360 C. The amount of air and water used was determined by previous experimentation on a sample of the tar acids fraction.

During the air blowing step about 200 to 800 parts of a product having an offensive odor. a high sulfur content and a specific gravity of about 0.991 was carried ofl. The residue containing the phenolates' was then dissolved in water, acidified and distilled to give a yield corresponding to 75 to 82 per cent of the original tar acids but with a specific gravity of 1.007; a sulfur content of 0.01 per cent and a decidedly phenolic odor. The product reacted favorably with formaldehyde and was comparable in specific gravity and otherwise to fractions of the same boiling range obtained from high temperature coal carbonization tar acids.

Example 4.--Four thousand (4000) parts of crude tar acids obtained by collecting the fraction distilling between 220-250 C. of cracked petroleum products,rwas found by analysis to I contain 0.69 percent of sulfur, 0.3 per cent of nitrogen bases, and 3.1 per cent of oils and naphthalene; its specific gravity was 1.005. This was dissolved in an aqueous solution containing 1200 parts of caustic soda; and the water solution of the phenolates after separation by decantation was concentrated as in Example 3, and oxidized by passing therethrough 15 cubic feet of air per gallon of tar acids used, which air had previously water vapor was forced through the mass for 45 minutes while maintaining the temperature at 340 C. The current of air was stopped, and the mass was diluted with 6000 cc. of water, cooled, discharged and sprung with sulfuric acid solution; at the neutral point, the tar acid was decanted anddistilled. Seventy (70) per cent of from high-temperature coal carbonization and,

having a specific gravity of 1.007 at 20 C.

The invention is further illustrated by the following: a

Example 3.Four thousand (4000) parts of a tar acids fraction, obtained by cracking petro upon analysis a content of 0.08 per cent of sulfur and a specific gravity at 15.6 C. of 0.9945. This was dissolved in an aqueous solution containing 1200 parts of caustic soda whereby the phenoper cent or more at the temperature of melting I .the mass, which temperature of course varies with leum and distilling between 230-240 C., showed 5 been bubbled through water heated to 9 0 C.

During the blowing step, the oil carried ofl was collected by passing the gases through a cooling condenser; and the neutral oil and phenols Dres- -ent in the condensate had specificgravities of .987 and .998 respectively. The phenolates remaining in the retort were then dissolved in wa-- ter. acidified to liberate the phenols, and the lat-'- ter were then distilled to yield a phenol mixture of a specific gravity. of 1.007, having a sulfur content of 0.042 per cent, and free from oil, naphthalene and nitrogen bases.

In the foregoing examples the concentration I of the aqueous solution was in general about 60 the fraction selection for treatment and the ingredients constituting the fraction. The amount of air saturated with water vapor at about 0. required is determined by a preliminary trial on a sample; but it ranges generally from about 10 to 15 cubic feet for each gallon of crude tar acid fraction treated. By controlling'the quantity of air and water vapor, the breaking of the side chain groups results largely in the fornlation of the useful phenol and methyl phenols fr the higher alkyl phenols. I K

What is claimed isi 1. Process of treating a crude tar acid fraction -I including a phenol with a side chain group longer than the methyl group which comprises extracting the acid content by aqueous caustic soda and asoaooe separating the aqueous layer, heating the aqmous layer to substantially dehydrate and melt the mass, passingthrough themas'sacurrentofair containing water vapor in amount to cause a breaking of the side chain group and to yield the sodium salt of a lower boiling phenoL'and acidilying to tree the lower boiling phenol.

2. In a process of treating a crude tar acid traction obtained in the cracking of petroleum and containing a phenol with a side chain group longer than the methyl group, the steps which comprise extracting the acid content by aqueous caustic soda and separating the aqueous layer, heating the aqueous layer to substantially dehydrateandmeltthemass, andpassingthrough the molten mass about ten to fifteen cubic ieet .a' dairpergallonotthetaracidiractionafter bubblingthroughwaterataboutm'C.

3. Processottreatingintheiormoithesodium salt a crudetar acidiraction including a phenol with a side chain' the methyl group 4. Process 01 splitting oil an alkyl group from;

a side chain on a phenol longer than the methyl group which comprises heating the sodium salt or the phenol to a molten state, and passing through the melt a current of air containing water vapor.

- VI'I'IORIO MOHNARI. 

